and he told of how his dad had asked him to explain where the photon comes from when an electron in an atom drops its orbital energy state down, and Feynman said that he couldn't really explain where the photon comes from that made sense in a way of thinking of the photon as a particle. This seems really basic to me as I don't think of photons as particles, and so when the moving charge (electron) changes it orbital state, this is a movement of charge which will create an electromagnetic field, and because the amount of charge movement is quantized by the allowable states of the electron orbits around an atom, it will emit a characteristic amount of electromagnetic energy. Labeling an amount or frequency of electromagnetic energy to be a photon particle makes no sense to me. I think a photon is really only a definition of magnitude, not an actual particle.
Jamie Morken wrote: I think a photon is really only a definition of magnitude,
Problem with that-- put a candle one foot from a square meter sized photocell. The photocell has a bazillion little particles of some photosensitive metal, say calcium, in ultra-fine powdered form. Each calcium particle is isolated form all the rest.
Let's say you get 10^18 electrons per second out of the photocell.
Now put a x10 filter between the two. So far so good, you now count
10^17 electrons per second. But then harbor-freight-physics has a sale, and you buy 16 more x10 filters. You put them between the candle and the photocell.
Now you're getting around one electron per second out of the photocell.
For a Nobel prize, please explain how an electromagnetic wave, spread out evenly over a square meter, can cause one electron to jump out.
For a second prize, explain why the electron sometimes jumps out after
1/10th of a second, when the electromagnetic wave hasnt delivered a full second's worth of energy,
You're wrong; those aren't Nobel-grade discoveries... and apparently both were made decades ago and are long known by physicists. The photoelectric effect is not proof of photons. Heh. Everything we know, is wrong. See:
Lamb W E and Scully M O 1969 The photoelectric effect without photons Polarization, Matiere et Rayonnement edn Soci=B4et=B4e Fran=B8caise de Physique (Paris: Presses Universitaires de France)
That "Lamb" is WIllis Lamb, who got the Physics Nobel in 1955
Some physicists even complain about the misconceptions spread by undergrad texts, such as the misconception that "Einstein's photoelectric effect proves the existence of photons." In fact the photoelectric effect can be explained by Classical EM fields if we allow vacuum fluctuations to exist. Photons may exist, but it takes a much more subtle experiment to prove this. A good article on this topic is by the author of the textbook "Quantum Optics" and is found in the collection below:
The concept of the photon-revisited A. Muthukrishnan, M. Scully, M. Zubairy
Found in "The Nature of Light: What Is a Photon?" Oct 2003 Optical Soc. of Am, Optics/Photonics News
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Other papers in the above collection are excellent. The discuss the real evidence for photons, and get us questioning the old incorrect textbook stuff were taught never to question ...and force us to (gasp) Actually Think!
Lest you assume that Lamb's paper was the last on this topic, please be aware that physicsts are STILL arguing over whether EM fields are quantized (whether photons actually exist,) and are still looking for experiments which supply an unequivocal answer. Zubairy mentions that these issues are discussed in Quantum Optics, but I've never tracked that one down. The whole OPA/OSN collection above has lots on this. And a quick google search turns up a recent paper from 2001:
Proposed experiment to test photon anticorrelation with quantitatively controllable source emission rate
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Abstract We describe a proposed experiment that will establish whether or not the optical field is quantized. We argue that previous attempts to establish this have not been conclusive. Quantum optics and Maxwell electrodynamics predict different outcomes for the experiment which is an improved version of that performed by Brown and Twiss in 1956 (Nature 177 27-9). The Brown-Twiss experiment did not distinguish between the two theories because its source was classical. In the proposed experiment, a weak light signal is achieved without selective deletion, and it can be either Poissonian or sub-Poissonian.
Myself, I believe in photons 90%, but have learned enough that I wouldn't be suprised if EM fields turn out to be real, and photons turn out to be a big and long-running mistake. The last big mistake was the Aether theory which was shot down by photons. It would be quite ironic if the physicists of a hundred years hence become convinced that neither Aether nor photons exist. :)
((((((((((((((((((((((( ( ( (o) ) ) ))))))))))))))))))))))) William J. Beaty Research Engineer snipped-for-privacy@chem.washington.edu UW Chem Dept, Bagley Hall RM74 snipped-for-privacy@eskimo.com Box 351700, Seattle, WA 98195-1700 ph425-222-5066 http//staff.washington.edu/wbeaty/
"Jamie Morken" wrote in message news:Hy51g.36035$WI1.10483@pd7tw2no...
Photons, EM fields, Electrons, Temperature Gradients, Laplacian, Vector Fields, etc... have nothing to do with nature. Nature was here long before man and is not constrained by how man interprets the world and defines things. Definitions are always circular, Systems can never be completely understood, etc...
The fact of the mater is that EM fields and photons are just our way of making something simple out of something that is infintely complex. Its your choice to choose which one you want to use to try and understand something or you can even try and come up with another model. Obviously though what we have today in science is a set of models that have worked very well... they could be totally off and just by chance we are able to get something out of them(well, the scientific method is what makes the difference between science and non-science).
One might define all things in the world as phenomena then find ways to "understand" that phenomena. The whole point is to predict future outcomes of similar phenomena so one can use that to there advantage. Quantum mechanics is based in the realm of probability theory(ofcours along with the theories it builds off of which involv other branches of math) applied to real world. Its a model one uses to help predict things.... does it say that it knows what reality is? It shoudln't. If it does then it is jumping into the world of philosophy or metaphysics. Its whole purpose is to explain phenomena. Classical mechanics uses calculus(although a bit of other branches of mathematics here and there) to explain the world. Both do a good job but neither has been perfect. As we learn more about the structure of representation(= math) we can then apply it to the real world(science).
The main thing I'm trying to get across is that all these theories are just models and try and explain how things work but cannot ever explain how things really are. We has humans have limited knowledge and are trying to make sense of the world in whatever way we can.... simplifications make this possible. If you are working on the theory of elasticity then it doesn't matter what a real photon is(if you could even know that). If its a small elf like creature then your crude approximation that it is a spherical massless particle might be good enough. Ofcourse it a photon could be totally different but the approximations we give it happen, for some unknown reason, to work. No one, EVER, will be able to definitively define what anything is. Some people act like they have a monopoly on intelligence and in those cases you gotta be careful about what they say. I studied physics for 4 years and I always thought that what I read and was told was how the world really was.... I could never except the quantum mechanical based reality(for obvious reasons because it is based on probability which by its nature allows is uncertain). When I took quantum mechanics I learned how probability theory was applied but I still had problems believing that was how reality really played its game. I finally learned through a prof that its just a model and they are not claiming that it is really what nature does(which I always believe but I never heard anyone else say).
So, if you didn't read all that the conclusion is that its up to you to choose which model you want to use to try and understand things better. The field interpretation may or may not work better than the discrete element method. You might even have to come up with your own definitions of things to get somewhere. In 99% of the cases you will be able to use the established theories to do what you need. You can rest comfortably knowing that millions of humans have worked over many centuries to build up these theories and test there validity. While I personally don't believe in quantum mechanics being a good approximation to reality I think it is a natural method to probe deeper into the universe(in the sense that we will be able to have better predictors).
ok, Mr Lamb was a big name. So were Newton, Kepler, Shockley and Pauling and they all went far off the deep end near the end of their careers. Lamb's article has dang few references to it on Google, so I'll assume it wasnt widely accepted.
Planck, Bohr, Einstein and Feynman all liked the photon theory, I'll take their word over J. Random Crank Theorist.
Pardon!!!! This makes no sense in relation to what you wrote.
Of course its a good *approximation* to reality. Indeed, its an excellent approximation. It predicts what is measured in reality extremely well. Thats why QM exists.
Kevin Aylward snipped-for-privacy@anasoft.co.uk
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SuperSpice, a very affordable Mixed-Mode Windows Simulator with Schematic Capture, Waveform Display, FFT's and Filter Design.
"There are none more ignorant and useless,than they that seek answers on their knees, with their eyes closed"
What I ment is that quantum mechanics is not a good approximation to reality in the sense that it is not how nature really works. Not that it isn't a good experimental predictor but that it doesn't "approximate" natures TRUE methods. Although you might say that they are one in the same it is easy to give examples where good predictors only look good on some scale but in the "long run" they fail. If quantum mechanics was one in the same as nature(i.e., nature used quantum mechanics) then on any scale it would be the same. Maybe approximation was a bad word to use there but not sure what else I could use. There are two concepts going on here though... one is the approximation to nature itself and one is the approximation to the experiment and predictions. Quantum mechanics surely does do a good job on the later but this is inherent in its methods(it uses probability and probably always, when used right, does more good than harm). We can never hope, at this point atleast, to understand the complexities of, say, a drop of water by modeling all its particles using the equations of fluid dynamics yet we can easily model it by using statistical methods. Ofcourse I doubt the particles themselfs care what method we use or how we think they work... they will do what they do... its our job to find out how they work and not there job to work like we want them to.
Note though even though QM predicts SOME things extremly well it doesn't predict all things well. But sure, if I didn't mention this then I should have, Theories are used to predict! If they can't predict well then they tend to be useless(although we can never be sure how close to nature the theory really is).
For example, Lets suppose you come up with a theory that explains some phenomena extremly well... lets say 99.9999%. Now I come up with another theory that explains the same phenomena only to about 30%. Does this mean your theory is a better representation to what nature uses? Maybe.. maybe not. My theory could be incomplete or have some errors that make it a bad predictor yet it could be exactly what nature does(hypothetically atleast).
QM is a bad representative of the what nature does UNLESS you really believe nature bases itself in the realm of probabilty... I doubt this though but who knows.
The point is that just because something is a good predictor of experiment doesn't mean it is how nature works(I might have already said that but). I do not believe, and it is my personal oppinion, that QM is how nature works... I doubt it even works by newtonian mechanics. It might even be impossible to know how it works. My point was to get across the idea that these are just theories that work well for some things and not explinations of how reality works. Is it a photon or an EM wave? probably niether... maybe both... Use what works to get somewhere. If its not working then try something else...
The apparent quantization of aether waves (aka "photons") is a result of the harmonic states of electron vibrational states in matter atoms. This doesn't mean that there are particles called photons, this only means that when matter emits aether waves from electron harmonic state changes (orbital changes of electrons) it emits the aether waves at a characteristic frequency based on the geometry of the atom, so it makes no sense to think there are particles of energy transmission called photons just because matter emits characteristic energy signatures. It is like saying that sound is quantized into "speech" particles because it so happens that there exists humans that emit sound waves at quantized frequencies.
So, howcome, if you surround an atom with photomultiplier tubes, and stimulate the atom to "[emit an] eather [wave] from electron harmonic state changes", only one of the PMTs registers?
No, I wanted to type the usual "Energy equals Planck's constant times 'nu'", but Greek characters don't usually show up properly in everybody's newsreader. Whatever; we all know how the units have to come out.
The quantization isn't "apparent", it's "real". To quote your OP:
Since the electrons' orbital energy states _are_ quantized (which is where Planck's constant actually comes in) the energy of the emitted photon must also be quantized.
We don't usually see this clearly and consistently because the orbitals' "natural" quantizations are thermalized, but that's another quibble. ;>)
There can be, but don't _have_ to be, harmonic relationships.
Nobody ever claimed that "particles of energy transmission called photons" have any objective existence, they're just a convenient way of parsing what we measure. And since the matter that emits them does so from quantized energy transitions, it's quite a natural way to parse those observations.
Did you have another source of time-varying, self-propagating EM waves in mind?
No. It's more like saying we can quantize the energy of phonons because the available energy levels for a lattice that supports them to vibrate in are quantized. But analogizing between light and sound is a Very Bad Idea for many reasons. Photons in free space are _not_ analogous to phonons in a lattice.
Who really knows? It could be some other factor involved that makes it "appear" this way.
I wouldn't be so sure. Many people claim a lot of stuff about physics that isn't quite true... Some of these people even have phd's in physics. There are "many" physicists that believe in negative probabilities.. quite nonsense. Probabilities are taken to be between 0 and 1 by definition/axiom... so its absurd to say there can be negative probabilities when we "define" them to be between 0 and 1.. but I've seen several physicists claim to the contrary. (and its a different story if you want to define probabilities to be between -1 and 0 or something like that... this is not what they do though.)
Or it could be that space and time itself is quantized!?!?!
Besides quantum atomic theory that works quite nicely, what do you have to say about accelerated electrons? On a bulk scale, sure, you just get synchrotron radiation, but on a subatomic level, a magnetic force photon comes in from the magnet, kicks the electron aside (ala Feynman diagram) and a radiation photon poops out for the change in kinetic energy.
Although I haven't done anything formal with Feynman diagrams, at least yet... but hey, that's the nice thing about the crucible of Usenet, if I'm wrong some flamer will correct it ;-)
Tim
--
Deep Fryer: a very philosophical monk.
Website: http://webpages.charter.net/dawill/tmoranwms
If you shoot a stream of electrons through an alternating magnetic field, like in a free-electron laser, there is an analog relationship between the oscillation of the free electron and the intensity of the magnetic field. It makes no sense that a free electron would only be influenced by quantum amounts of magnetic field energy.
You can change the gap between the two magnet arrays to change the magnetic force on the electrons to any field intensity, so the magnetic field energy is not quantized. (see: "
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I wasn't aware you could do anything formal with Feynman diagrams? :)
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